Bonded structures

ABSTRACT

A bonded structure can include a first element having a first interface feature and a second element having a second interface feature. The first interface feature can be bonded to the second interface feature to define an interface structure. A conductive trace can be disposed in or on the second element. A bond pad can be provided at an upper surface of the first element and in electrical communication with the conductive trace. An integrated device can be coupled to or formed with the first element or the second element.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 15/849,383,filed Dec. 20, 2017, titled “BONDED STRUCTURES,” issued Dec. 31, 2019 asU.S. Pat. No. 10,522,499, which claims priority to U.S. ProvisionalPatent Application No. 62/457,116, filed Feb. 9, 2017, titled “BONDEDSTRUCTURES,” and U.S. Provisional Patent Application No. 62/458,441,filed Feb. 13, 2017, titled “BONDED STRUCTURES,” the entire disclosuresof which are hereby incorporated herein by reference.

BACKGROUND Field

The field generally relates to bonded structures, and in particular, tobonded structures having a reduced lateral footprint.

Description of the Related Art

In semiconductor device fabrication and packaging, some integrateddevices are sealed from the outside environs in order to, e.g., reducecontamination or prevent damage to the integrated device. For example,some microelectromechanical systems (MEMS) devices include a cavitydefined by a cap attached to a substrate with an adhesive such assolder. However, some adhesives may be permeable to gases, such that thegases can, over time, pass through the adhesive and into the cavity.Moisture or some gases, such as hydrogen or oxygen gas, can damagesensitive integrated devices. Other adhesives, such as solder, createtheir own long term reliability issues. Accordingly, there remains acontinued need for improved seals for integrated devices.

Furthermore, regardless of whether the devices are sealed from theoutside environs, or whether the device includes a cavity, in varioustypes of bonded structures, bond pads for connecting to externaldevices, substrates, or other elements may occupy valuable space or areain the package or on the device. It can thus be desirable to provide abonded structure in which the lateral footprint of the package or deviceis reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic side sectional view of a bonded structure,according to various embodiments.

FIGS. 1B-K are partial schematic sectional plan views of variousembodiments of an interface structure defined along a bonded interfaceof the bonded structure.

FIG. 2A is a schematic sectional plan view of an interface structure ofthe bonded structure shown in FIGS. 1A-1B.

FIG. 2B is a schematic sectional plan view of an interface structurehaving one or more electrical interconnects extending through the bondedinterface.

FIG. 2C is a schematic sectional plan view of the interface structure ofFIG. 1C.

FIG. 2D is a schematic sectional plan view of an interface structurehaving a plurality of conductive interface features disposed about acavity to define an effectively annular profile, with each conductiveinterface feature comprising a mostly annular profile.

FIG. 2E is a schematic sectional plan view of an interface structurehaving a plurality of conductive interface features disposed about acavity to define an effectively annular profile, wherein the pluralityof conductive features comprises a plurality of segments spaced apart bygaps.

FIG. 2F is a schematic side sectional view of a bonded structure,according to some embodiments.

FIG. 2G is a schematic side sectional view of a bonded structure,according to various embodiments.

FIGS. 2H and 2I are schematic plan views of interface structures thatcomprise conductive interface features including an array of conductivedots or other discrete shapes, as viewed from the plan view.

FIG. 2J is a schematic side sectional view of a bonded structure havingone or more bond pads positioned outside a bonded interface betweenfirst and second elements.

FIG. 2K is a top plan view of the bonded structure shown in FIG. 2J.

FIG. 2L is a schematic side sectional view of a bonded structure havingone or more bond pads disposed on an upper surface of the bondedstructure, according to various embodiments.

FIG. 2M is a top plan view of the bonded structure shown in FIG. 2L.

FIG. 2N is a chart that plots the percent increase in the number ofbonded structures or dies per wafer versus die area for bondedstructures in which bond pad ledges have been eliminated on one side,two sides, three sides, or four sides of the bonded structure or die.

FIG. 2O is a schematic side sectional view of a bonded structure,according to another embodiment.

FIG. 3 is a schematic side sectional view of a portion of a bondedstructure that includes a crack stopper connected with the conductiveinterface features of the interface structure.

FIGS. 4A-4C are schematic plan views of bonded structures that increasetolerance for misalignments when corresponding interface features arebonded together.

FIGS. 5A-5D are schematic plan views of an interface structure thatincreases tolerance for misalignments when corresponding interfacefeatures on each semiconductor element are bonded together.

FIGS. 6A-6B are schematic plan views of an interface structure thatincreases tolerance for misalignments when corresponding interfacefeatures on each semiconductor element are bonded together, according toanother embodiment.

FIG. 7A is a schematic plan view of a conductive interface feature inwhich a plurality of inner regions of non-conductive interface featuresare disposed within a crosswise grid structure defined by intersectingconductive interface features.

FIG. 7B is a schematic plan view of a bonded interface structure formedby bonding two interface features.

FIG. 7C is a schematic plan view of the bonded interface structure ofFIG. 7B, with a plurality of electrical interconnects disposed withininner regions of the non-conductive interface feature.

FIG. 8 is a schematic diagram of an electronic system incorporating oneor more bonded structures, according to various embodiments.

DETAILED DESCRIPTION

Various embodiments disclosed herein relate to interface structures thatconnect two elements (which may comprise semiconductor elements) in amanner that effectively seals integrated devices of the semiconductorelements from the outside environs. For example, in some embodiments, abonded structure can comprise a plurality of semiconductor elementsbonded to one another along an interface structure. An integrated devicecan be coupled to or formed with a semiconductor element. For example,in some embodiments, the bonded structure can comprise amicroelectromechanical systems (MEMS) device in which a cap (a firstsemiconductor element) is bonded to a carrier (a second semiconductorelement). A MEMS element (the integrated device) can be disposed in acavity defined at least in part by the cap and the carrier.

In some arrangements, the interface structure can comprise one or moreconductive interface features disposed about the integrated device, andone or more non-conductive interface features to connect the first andsecond semiconductor elements and to define an effectively annular oreffectively closed profile. In some embodiments, the interface structurecan comprise a first conductive interface feature, a second conductiveinterface feature, and a solid state non-conductive interface featuredisposed between the first and second conductive interface features. Insome embodiments, each semiconductor element can comprise an associatedconductive interface feature, and the conductive interface features canbe directly bonded to one another to connect the two semiconductorelements.

Various embodiments disclosed herein relate to stacked and bondedstructures for reducing the overall lateral footprint of the device orpackage. The connective interface features can connect through the uppersurface of the two semiconductor elements to electrically connect tobond pads on the upper surface of the upper element with metallic tracesformed in one or more of the two elements. The bond pads can provideelectrical interconnection for integrated devices within one or both ofthe semiconductor elements, including any devices (e.g., MEMS) exposedto any cavity defined between the elements, thus obviating separate bondpads outside the real estate of the upper element. The cavity can beformed within the upper element, within the upper element, or by theupper and lower elements. Accordingly, the lateral extent of the bondedstructure can be reduced.

FIG. 1A is a schematic side sectional view of a bonded structure 1,according to various embodiments. FIG. 2A is a schematic sectional planview of an interface structure 10 of the bonded structure 1 shown inFIGS. 1A-1B. The bonded structure 1 can include a first semiconductorelement 3 bonded to a second semiconductor element 2 along the interfacestructure 10. As explained herein, corresponding bonding layers 11 ofthe first and second semiconductor elements 3, 2 can be directly bondedto one another without an intervening adhesive. As explained below, theinterface structure 10 can include conductive interface features 12embedded in a surrounding non-conductive interface feature 14. Invarious embodiments, a barrier or seed layer (not illustrated) can beprovided on the non-conductive interface feature 14, e.g., lining atrench formed in the feature 14. The conductive interface feature 12(which may comprise, e.g., copper) can be provided over the barrierlayer, if present. The barrier layer can comprise any suitable materialthat can prevent migration of the material of the conductive interfacefeature 12 into the non-conductive feature 14. For example, in variousembodiments, the barrier layer can comprise an insulating material, suchas silicon nitride (SiN), or a conductive material, such as titanium(Ti), titanium nitride (TiN), titanium tungsten (TiW), tantalum (Ta),tantalum nitride (TaN), etc. Multiple lining layers can be provided toserve as barriers and/or to electrically isolate the conductiveinterface feature 12.

As explained herein, the bonding layers 11 of each element 3, 2 caninclude conductive and non-conductive interface features that can bondto define a seal. As shown in FIG. 1A, the interface features 12, 14 canextend vertically into the semiconductor elements (e.g., into andthrough the bonding layers 11), such that the interface features 12, 14can extend in a direction from one semiconductor element towards theother semiconductor element, e.g., vertically relative to the bondedstructure. In various embodiments, the interface features 12 can extendfrom the bond interface entirely into each semiconductor substrate ofeach semiconductor element on either side of the bond interface. Thefirst and second semiconductor elements can define a cavity 5 in whichan integrated device 4 is at least partially disposed. In theillustrated embodiment, the first semiconductor element 3 can comprise acap that is shaped to define the cavity, or that is disposed over acavity in the second semiconductor element 2. For example, thesemiconductor element 3 can comprise a wall 6 disposed about theintegrated device 4 and separating the cavity 5 from the outsideenvirons. In various embodiments, the wall 6 and cap can comprise asemiconductor material, such as silicon. In other embodiments, the wall6 and cap can comprise a polymer, ceramic, glass, or other suitablematerial. The cavity 5 can comprise an air cavity, or can be filled witha suitable filler material or gas. Although the first and secondelements 2, 3 are described herein as semiconductor elements, in otherembodiments, the first and second elements 2, 3 can comprise any othersuitable type of element, which may or may not comprise a semiconductormaterial. For example, the elements 2, 3 can comprise various types ofoptical devices in some embodiments that may not comprise asemiconductor material. In other embodiments, optical devices maycomprise a semiconductor material.

The second semiconductor element 2 can comprise a carrier having anexterior surface 9 to which the first semiconductor element 3 is bonded.In some embodiments, the carrier can comprise a substrate, such as asemiconductor substrate (e.g., a silicon interposer with conductiveinterconnects), a printed circuit board (PCB), a ceramic substrate, aglass substrate, or any other suitable carrier. In such embodiments, thecarrier can transfer signals between the integrated device 4 and alarger packaging structure or electronic system (not shown). In someembodiments, the carrier can comprise an integrated device die, such asa processor die configured to process signals transduced by theintegrated device 4. In the illustrated embodiment, the integrateddevice 4 comprises a MEMS element, such as a MEMS switch, anaccelerometer, a gyroscope, etc. The integrated device 4 can be coupledto or formed with the first semiconductor element 3 or the secondsemiconductor element 2.

In some configurations, it can be important to isolate or separate theintegrated device die 4 from the outside environs, e.g., from exposureto gases and/or contaminants. For example, for some integrated devices,exposure to moisture or gases (such as hydrogen or oxygen gas) candamage and/or change the performance of the integrated device 4 or othercomponents. Accordingly, it can be important to provide an interfacestructure 10 that effectively or substantially seals (e.g., hermeticallyor near-hermetically seals) the cavity 5 and the integrated device 4from gases. As shown in FIGS. 1A and 2A, the interface structure 10 canbe arranged to prevent gases from passing through the interfacestructure 10 from an outer surface 8 of the structure 1 to an innersurface 7 of the structure 1.

The disclosed embodiments can utilize materials that have low gaspermeation rates and can arrange the materials so as to reduce oreliminate the entry of gases into the cavity 5. For example, thepermeation rate of some gases (such as hydrogen gas) through metals maybe significantly less that the permeation rate of gases through othermaterials (such as dielectric materials or polymers). Hydrogen gas, forexample, may dissociate into its component atoms at or near the outersurface 8. The dissociated atoms may diffuse through the wall 6 orinterface structure 10 and recombine at or near the inner surface 7. Thediffusion rate of hydrogen gas through metal can be approximatelyproportional to the square root of the pressure. Other gases, such asrare gases, may not permeate metals at all. By way of comparison, gasesmay pass through polymer or glass (silicon oxide) materials faster(e.g., proportional to the pressure) than metal materials since the gasmolecules may pass through without dissociating into atoms at the outerwall 8, or the metal materials may have lower diffusivity to the gases.

Accordingly, the embodiments disclosed herein can beneficially employmetal that defines an effectively annular or closed pattern (see FIGS.2A-2E) about the integrated device 4 to seal an interior region of thebonded structure (e.g., the cavity 5 and/or integrated device 4) fromthe outside environs and harmful gases. Beneficially, in someembodiments, the metal pattern can comprise a completely closed looparound the integrated device 4, which may improve sealing relative toother arrangements. In some embodiments, the metal pattern can comprisean incompletely annular pattern, e.g., mostly or partially annular,about the device 4, such that there may be one or more gaps in themetal. Since the permeation rate of gases through metals (such ascopper) is less than the permeation rate of gases through dielectric ornon-conductive materials (such as silicon oxide, silicon nitride, etc.),the interface structure 10 can provide an improved seal for an interiorregion of the bonded structure 1.

However, in some embodiments, it may be undesirable to utilize aninterface structure 10 that includes only metal or a significant widthof metal lines. If the interface structure 10 includes wide metal linesor patterns, then the metal may experience significant dishing duringchemical mechanical polishing (CMP) or other processing steps. Dishingof the metal lines can adversely affect ability to bond the metal linesof first semiconductor element 3 to the second semiconductor element 2,particularly when employing direct hybrid metal-to-metal anddielectric-to-dielectric bonding techniques. Accordingly, in variousembodiments, the interface structure 10 can include one or moreconductive interface features 12 embedded with or otherwise adjacent toone or more non-conductive interface features 14. The conductiveinterface features can provide an effective barrier so as to prevent orreduce the permeation of gases into the cavity 5 and/or to theintegrated device 4. Moreover, the conductive interface features can bemade sufficiently thin and can be interspersed or embedded with thenon-conductive interface features so as to reduce or eliminate thedeleterious effects of dishing.

In some embodiments disclosed herein, the interface structure 10 can bedefined by first interface features on the first semiconductor elementand second interface features on the second semiconductor element. Thefirst interface features (including conductive and non-conductivefeatures) can be bonded to the corresponding second interface featuresto define the interface structure 10. In some embodiments, the interfacestructure 10 can comprise a separate structure that is separately bondedto the first semiconductor element 3 and the second semiconductorelement 2. For example, in some embodiments, the wall 6 may be providedas a separate open frame with a generally planar semiconductor element 3provided facing the frame. A second interface structure (not shown) cancomprise an intervening structure that is directly bonded without anintervening adhesive between the open frame and semiconductor element 3thereby forming a similar enclosed cavity 5 to that shown in FIG. 1A.The interface structure(s) 10 may provide mechanical and/or electricalconnection between the first and second semiconductor elements 3, 2. Insome embodiments, the interface structure 10 may provide only amechanical connection between the elements 3, 2, which can act to sealthe cavity 5 and/or the integrated device 4 from the outside environs.In other embodiments, the interface structure 10 may also provide anelectrical connection between the elements 3, 2 for, e.g., groundingand/or for the transmission of electrical signals. As explained in moredetail below in connection with FIGS. 4A-7C, the conductive interfacefeatures can be direct bonded to one another without an interveningadhesive and without application of pressure, heat, and/or a voltage.For example, bonding surfaces (e.g., bonding layers 11) of first andsecond interface features can be prepared. The bonding surfaces can bepolished or planarized, activated, and terminated with a suitablespecies. For example, in various embodiments, the bonding surfaces canbe polished to a root-mean-square (rms) surface roughness of less than 1nm, e.g., less than 0.5 nm. The polished bonding surfaces can beactivated by a slight etch or plasma termination. In variousembodiments, the bonding surfaces can terminated with nitrogen or anitrogen containing species, for example, by way of etching using anitrogen-containing solution or by using a plasma etch with nitrogen. Asexplained herein, the bonding surfaces can be brought into contact toform a direct bond without application of pressure. In some embodiments,the semiconductor elements 3, 2 can be heated to strengthen the bond,for example, a bond between the conductive features. Additional detailsof direct bonding methods may be found at least in U.S. Pat. Nos.9,385,024; 9,391,143; and 9,431,368, the entire contents of which areincorporated by reference herein in their entirety and for all purposes.In some embodiments, the conductive interface features 12 of bothelements 3, 2 and the non-conductive interface features 14 of bothelements 3, 2 are simultaneously directly bonded to one another. Inother embodiments, the non-conductive interface features 14 can first bedirectly bonded to one another, then conductive interface features 12can subsequently be directly bonded to one another after a thermaltreatment that preferentially expands conductive interface features 12that are dished or slightly recessed, for example less than 20 nm or 10nm from adjacent non-conductive interface features 14.

It should be appreciated that, although the illustrated embodiment isdirected to a MEMS bonded structure, any suitable type of integrateddevice or structure can be used in conjunction with the disclosedembodiments. For example, in some embodiments, the first and secondsemiconductor elements can comprise integrated device dies, e.g.,processor dies and/or memory dies. In addition, although the disclosedembodiment includes the cavity 5, in other arrangements, there may notbe a cavity. For example, the embodiments disclosed herein can beutilized with any suitable integrated device or integrated device die inwhich it may be desirable to seal active components from the outsideenvirons and gases. Moreover, the disclosed embodiments can be used toaccomplish other objectives. For example, in some arrangements, thedisclosed interface structure 10 can be used to provide anelectromagnetic shield to reduce or prevent unwanted electromagneticradiation from entering the structure 1, and/or to prevent various typesof signal leakage. Of course, the cavity may be filled with any suitablefluid, such as a liquid, gas, or other suitable substance which mayimprove, for example, the thermal, electrical or mechanicalcharacteristics of the structure 1.

FIGS. 1B-1K are schematic, partial, sectional plan views of variousembodiments of the interface structure 10. It will be understood thatthe illustrated patterns can extend completely annularly or incompletelyannularly (e.g., mostly annularly), around the protected region, such asthe cavity 5 of FIG. 1A, to define an effectively annular or effectivelyclosed profile. As used herein, effectively annular structures mayinclude round annular structures, as well as non-rounded annularstructures that define an effectively closed profile (e.g., square orother polygon). As shown in FIGS. 1B-1K, the interface structure 10 cancomprise one or a plurality of conductive interface features 12 and oneor a plurality of non-conductive interface features 14. As shown in FIG.1A, the conductive and non-conductive features 12, 14 can extendvertically through portions of the first and/or second semiconductorelements 3, 2, e.g., vertically through portions of the bonding layer(s)11. For example, the conductive and non-conductive features 12, 14 canextend vertically through the first and/or second semiconductor elements3, 2 (e.g., in a direction non-parallel or perpendicular to the majorsurface of the semiconductor elements 3, 2) by a vertical distance of atleast 0.05 microns, at least 0.1 microns, at least 0.5 microns, or atleast 1 micron. For example, the conductive and non-conductive features12, 14 can extend vertically through the first and/or secondsemiconductor elements 3, 2 by a vertical distance in a range of 0.05microns to 5 microns, in a range of 0.05 microns to 4 microns, in arange of 0.05 microns to 2 microns, or in a range of 0.1 microns to 5microns. By extending the conductive and non-conductive features 12, 14through portions of the first and/or second semiconductor elements 3, 2,the conductive and non-conductive features 12, 14 of the interfacestructure 10 can provide a seal without gaps between the semiconductorelements 3, 2. For example, in various arrangements, if conductive andnon-conductive features 12, 14 are extended into the semiconductorsubstrate portion of elements 3, 2, a preferred seal comprised of onlysemiconductor and metal can be formed. The conductive and non-conductivefeatures 12, 14 provided on semiconductor elements 3, 2 may providegenerally planar surfaces for bonding the two semiconductor elements.

The conductive interface feature 12 can comprise any suitable conductor,such as a metal. For example, the conductive interface feature 12 cancomprise copper, nickel, tungsten, aluminum, or any other suitable metalthat is sufficiently impermeable to fluids/gases, such as air, hydrogen,nitrogen, water, moisture, etc. The non-conductive interface feature 14can comprise any suitable non-conductive material, such as a dielectricor semiconductor material. For example, the non-conducive interfacefeature 14 can comprise silicon oxide or silicon carbide nitride in someembodiments. Beneficially, the use of both a conductive interfacefeature 12 and a non-conductive interface feature 14 can provideimproved sealing to prevent gases from passing from the outside environsinto the cavity 5 and/or to the device 4 and vice versa. As explainedabove, conductors such as metals may generally provide improved sealingfor many gases. However, some non-conductive materials (e.g.,dielectrics) may be less permeable to certain gases than conductors,metals, or semiconductors. Structurally mixing the conductive features12 with the non-conductive features 14 may provide a robust seal toprevent many different types of gases and other fluids from entering thecavity and/or affecting the device 4.

In the embodiment of FIG. 1B, only one conductive interface feature 12,which may be completely annular, is provided. The conductive interfacefeature 12 can be embedded in one or more non-conductive interfacefeatures 14 to define an effectively annular or effectively closedprofile. For example, in some embodiments, the conductive interfacefeature 12 can be embedded in a bulk non-conductive material. In otherembodiments, layers of non-conductive material can be provided onopposing sides of the conductive interface feature 12. As shown in FIG.2A, the conductive interface feature 12 can extend around the cavity 5and/or the integrated device 4 in a completely annular pattern. In FIG.2A, for example, the conductive interface feature 12 extends in acomplete annulus, or closed shape, about the cavity 5 and/or device 4,such that the non-conductive material of the non-conductive feature 14does not cross or intersect the conductive interface feature 12. Inother embodiments, however (for example, see description of FIGS. 2D and2E below), there may be one or more gaps between portions of theconductive interface feature 12, but without a direct path to the cavity5. Individual elements of the conductive interface feature 12 can beincompletely annular in some embodiments. For example, individualelements of the conductive interface feature 12 can be mostly annular,e.g., extend about the cavity 5 and/or the integrated device 4 by atleast 180°, at least 270°, at least 350°, or at least 355° (e.g., 360°),while cooperating to define an effectively annular or closed interfacestructure 10. Further, as explained above, the conductive interfacefeature 12 can extend vertically into and can be embedded in portions ofthe wall 6 and/or corresponding portions of the second semiconductorelement 2.

The structure of FIG. 1A, including any of the example patterns of FIGS.1B-1K, can be formed, for example, by semiconductor fabricationtechniques, such as by forming metal lines on a substrate by deposition,patterning and etching and depositing oxide thereover, or by damasceneprocessing. Desirably, the metal lines to be bonded are formed flushwith surrounding non-conductive material, or slightly (e.g., 0.5 nm to20 nm) recessed or protruding from the non-conductive material. Annularor mostly annular patterns of metal lines can be formed on bothsemiconductor elements 3, 2 using semiconductor processing, for directlybonding to one another and creating an effective metal seal against gasdiffusion.

The interface structure 10 can have an interface width to in a range of1 micron to 1 mm, in a range of 0.1 microns to 100 microns, in a rangeof 0.1 microns to 50 microns, in a range of 1 micron to 25 microns, in arange of 0.1 microns to 10 microns, in a range of 0.1 microns to 1micron, or in a range of 1 micron to 10 microns. The conductiveinterface feature 12 can have a conductor width t_(c) in a range of 0.1microns to 50 microns. The non-conductive interface feature 14 can havenon-conductor widths t_(i) in a range of 0.1 micron to 1 mm, in a rangeof 0.1 microns to 100 microns, in a range of 0.1 microns to 50 microns,in a range of 1 micron to 25 microns, in a range of 0.1 microns to 10microns, in a range of 0.1 microns to 1 micron, or in a range of 1micron to 10 microns. As explained above, the interface structure 10disclosed in FIG. 1B can beneficially provide an effective seal againstgases entering the cavity 5 and/or interacting with the device 4.Moreover, the interface structure 10 disclosed herein can be narrower inthe horizontal dimension than other types of bonds or interfaces for agiven bond strength, which can advantageously reduce the overall packagefootprint. In various embodiments, the interface structure 10 can bemostly or entirely defined by the non-conductive feature 14 (e.g., adielectric), such that most or the entire bonded interface comprises anon-conductive material. As explained above, the width t_(i) of theinsulator can be made very narrow (e.g., in a range of 1 microns to 100microns, or in a range of 1 micron to 50 microns) while also providing asufficiently strong bonding interface between the elements.

Turning to FIG. 1C, the interface structure 10 can include a pluralityof conductive interface features 12 and an intervening solid state(e.g., non-gaseous) non-conductive interface feature 14 disposed betweenadjacent conductive interface features 12. FIG. 2C is a schematic planview of the interface structure 10 shown in FIG. 1C. As with theimplementation of FIG. 1B, the interface structure 12 can be disposedabout the integrated device 4 and can comprise conductive features 12arranged in an effectively annular or closed profile (e.g., a completeor incomplete annulus in various arrangements) to connect the firstsemiconductor element 3 and the second semiconductor element 2. In FIGS.1C and 2C, the conductive features 12 comprise at least one complete orabsolute annulus. In other embodiments, the conductive features can beshaped differently, but can be arranged to define an effectively annularor closed profile. The use of multiple conductive features 12 canprovide multiple layers of highly impermeable material so as to reducethe inflow of gases into the cavity 5. Utilizing multiple thinconductive features 12 spaced by the non-conductive features 14,compared to wider features, can reduce the effects of dishing due topolishing for a given degree of overall impermeability. Thus, in variousembodiments, multiple conductive features 12 can be arranged around oneanother, for example concentrically, mostly or completely about thedevice 4 and/or the cavity 5 to provide an effective gas seal.

Moving to FIG. 1D, in some embodiments, the conductive interfacefeatures 12 can comprise a plurality of annular conductors 12A disposedabout the cavity 5 and/or device 4 in an effectively annular or closedpattern, and a plurality of crosswise conductors 12B connecting adjacentannular conductors 12A. Advantageously, the use of annular and crosswiseconductors 12A, 12B can provide increased contact area forimplementations that utilize direct bonding (explained below), and canprovide an improved gas seal due to the beneficial permeation propertiesof the conductive material. As with the embodiments of FIGS. 1B-1C, inFIG. 1D, the conductive interface features 12 can delimit a closed loopsuch that the non-conductive features 14 do not intersect or cross theconductive features 12.

FIGS. 1E-1G illustrate conductive interface features 12 having a kinked,annular profile, in which a plurality of conductive segments 112 a-112 care connected end-to-end and angled relative to adjacent segments. Aswith the embodiments of FIGS. 1B-1D, the features 12 can be disposedabout the cavity 5 and/or device 4 in an effectively annular or closedpattern, e.g., in a complete annulus. The kinked profiles illustrated inFIGS. 1E-1G can comprise a first segment 112 a and a second segment 112c spaced apart from one another in a transverse direction. The first andsecond segments 112 a, 112 c can be connected by an interveningtransverse segment 112 b. The first and second segments 112 a, 112 c canbe oriented along a direction generally parallel to the at leastpartially annular pathway around the cavity 5 and/or integrated device4. The transverse segment 112 c can be oriented transverse ornon-parallel to the first and second segments 112 a, 112 c. In someembodiments, the non-conductive interface features 14 may not cross theconductive features 12.

The kinked annular profile of the conductive interface features 12 canfacilitate direct bonding with increased tolerance for misalignment, ascompared with features 12 that are straight or non-kinked, whilemaintaining the benefits of narrow lines with respect to the effects ofdishing after polishing. For example, the conductive interface features12 may be sufficiently thin so as to reduce the effects of dishing butmay traverse a pattern that facilitates alignment for bonding. Thekinked profile can include any number of conductive interface features12. For example, FIG. 1E illustrates a kinked profile with a singleconductive interface feature 12. FIG. 1F illustrates a plurality ofconductive interface features 12 spaced apart transversely by anintervening non-conductive interface feature 14. As with FIG. 1D, inFIG. 1G, spaced apart annular conductors 12A can be joined by crosswiseconductors 12B. Skilled artisans would appreciate that other patternsmay be suitable.

FIGS. 1H-1K illustrate conductive interface features 12 having anirregular or zigzag annular profile, in which a plurality of conductivesegments 112 a-112 f are connected end-to-end and angled relative toadjacent segments by way of one or more bend regions 11. As shown inFIGS. 1H-1K, the segments 112 a-112 f may be arranged in an irregularpattern, in which the segments 112 a-112 f are angled at differentorientations and/or have different lengths. In other arrangements, thesegments 112 a-112 f may be arranged in a regular pattern at angles thatare the same or periodic along the annular profile. In still otherarrangements, each segment 112 a-112 f of the conductive features 12 canbe curved or otherwise non-linear. These features may also increasetolerance for misalignment, relative to straight line segments, whilestill employing relatively narrow lines that are less susceptible todishing and therefore easier to employ in direct metal-to-metal bonding.

FIG. 2B is a schematic sectional plan view of an interface structure 10having one or more electrical interconnects extending through theinterface structure 10. As with FIG. 2A, the conductive feature(s) 12can be disposed within the interface structure 10 about the cavity 5and/or integrated device 4 to define an effectively annular or closedprofile, e.g., a completely annular profile. The conductive feature(s)12 can comprise elongate feature(s) with a length greater than a width(e.g., with a length of at least five times the width, or at least tentimes the width). Unlike the interface structure 10 shown in FIG. 2A,however, the interface structure 10 of FIG. 2B includes one or aplurality of electrical interconnects 20 extending vertically throughone or more non-conductive interface features 14. The electricalinterconnect(s) 20 can be in electrical communication with theintegrated device 4 and/or other components of the bonded structure 1 soas to transfer signals between the various components of the structure1. In some embodiments, the electrical interconnect(s) 20 can extendfrom the first semiconductor element 3 to the second semiconductorelement 2. As shown in FIG. 2B, the electrical interconnect(s) 20 can bespaced inwardly and electrically separated from the conductive interfacefeature 12, which itself can also serve to electrically connect circuitsin the first and second semiconductor elements 3, 2. In otherembodiments, the electrical interconnect(s) 20 can be spaced outwardlyfrom the conductive interface feature 12. In still other embodiments, asexplained below, the electrical interconnect(s) 20 can extend throughintervening non-conductive interface features 14 disposed between aplurality of conductive interface features 12.

The electrical interconnects 20 can provide electrical communicationbetween the semiconductor elements 3, 2 through the interface structure10. Providing the interconnects 20 in a direction non-parallel ortransverse to the interface structure 10 can therefore enable theinterface structure 10 to act as both a mechanical and electricalconnection between the two semiconductor elements 3, 2. Theinterconnects 20 can comprise any suitable conductor, such as copper,aluminum, gold, etc. The interconnects 20 can comprise conductive tracesor through-silicon vias in various arrangements. Moreover, as notedabove, the interface features 12 may also serve as annular or mostlyannular electrical interconnects, with or without the conventionalinterconnects 20.

FIG. 2D is a schematic sectional plan view of an interface structure 10having a plurality of conductive interface features 12A, 12B disposedabout a cavity 5 to define an effectively annular or closed profile,with each conductive interface feature 12A, 12B comprising anincompletely annular feature, e.g., a mostly annular feature extendingmore than 180°. For example, as shown in FIG. 2D, each conductiveinterface feature 12A, 12B can comprise a U-shaped structure, with thefeature 12B disposed inwardly relative to the feature 12A by anon-conductive gap 39. Thus, in FIG. 2D, each conductive interfacefeature 12A, 12B may comprise a mostly annular profile, but with the gap39 between the two interface features 12A, 12B such that any one of theinterface features 12A, 12B does not necessarily define a closed loop.The structure 10 shown in FIG. 2D may still be effective at reducing thepermeation of gases into cavity 5 and/or device 4, since the pattern ofconductive interface features 12A, 12B combine to create an effectivelyannular or effectively closed structure about the cavity 5. Some gas maypermeate through the gap 39, but the gas would have a very long paththrough the non-conductive material before it could reach the cavity 5and/or contact the device 4, so as to overcome the higher diffusivity ofgases in the non-conductive material 14 relative to the conductivematerial of the conductive interface features 12A, 12B. It should beappreciated that although two features 12A, 12B are shown herein, anysuitable number of features 12 can be used.

FIG. 2E is a schematic sectional plan view of an interface structure 10having a plurality of conductive interface features 12 disposed about acavity 5 to define an effectively annular or closed profile, wherein theplurality of conductive features 12 comprises a plurality of segmentsspaced apart by non-conductive gaps 39. The segments that define eachconductive interface feature 12 shown in FIG. 2E comprise linearsegments, but in other embodiments, the segments can be curved. In FIG.2E, some or all conductive interface features 12 on their own may notdefine a mostly annular pattern. Taken together, however, the patterndefined by the illustrated arrangement of conductive interface features12 may define an effectively annular or closed pattern. Thus, eventhough a particular conductive interface feature 12 may not be annular,the arrangement of multiple conductive interface features 12 can definean effectively annular or closed pattern to seal an interior region ofthe bonded structure from gas entering the interior region from theoutside environs, as shown in FIG. 2E.

The embodiments of FIGS. 2A-2E can accordingly comprise interfacestructures 10 that include conductive and non-conductive interfacefeatures 12, 14 that collectively define an effectively annular orclosed diffusion barrier. For example, a particular conductive interfacefeature 12 can comprise a complete annulus or an incomplete annulus(e.g., mostly annular) that is arranged with other conductive andnon-conductive interface features so as to define an effectively annularpattern or diffusion barrier. In some embodiments, the conductiveinterface feature can comprise other shapes, such as straight or curvedsegments, that are arranged about the cavity 5 and/or device 4 so as todefine an effectively annular pattern or diffusion barrier. Moreover,the embodiments of FIGS. 2D and 2E can advantageously provide multipleconductive segments that can each serve as separate electricalconnections, for example, for separate signal line connections, groundline connections and power line connections. Together those segments canprovide effectively annular conductive patterns to serve as diffusionbarriers. The effectively annular patterns described herein canbeneficially provide a longer distance over which gases travel to reachthe sensitive components of the structure 1, which can reduce thepermeability of the structure 1.

FIG. 2F is a schematic side sectional view of a bonded structure 1,according to some embodiments. FIG. 2F is similar to FIG. 1A, except inFIG. 2F, the first semiconductor element 3 can comprise one or aplurality of electronic components 38 formed or coupled with variousportions of the semiconductor element 3. For example, as illustrated,the semiconductor element 3 can comprise a plurality of electroniccomponents 38A-38C. The electronic components 38A-38C can comprise anysuitable type of electronic component. The electronic components 38 cancomprise any suitable type of device, such as integrated circuitry(e.g., one or more transistors) or the like. In some embodiments, theelectronic components 38 can communicate with the device 4, the secondsemiconductor element 2, and/or other components by way of theinterconnects (see FIG. 2B) and/or by the conductive interface features12. For example, the electronic components 38 can communicate with thesecond semiconductor element 2 by way of one or more conductive traces36 that pass through the semiconductor element 3. The electroniccomponents 38 and the traces 36 can be defined by semiconductorprocessing techniques, such as deposition, lithography, etching, etc.and can be integrated with the semiconductor element 3. The traces, forexample, may be formed by conventional back-end-of-line interconnectmetallization through multiple metal levels. Moreover, as shown in FIG.2F, any of the embodiments disclosed herein can include one or aplurality of electronic components 37 formed (e.g., with semiconductorprocessing techniques) or coupled with the second semiconductor element2. The electronic components 37 can comprise any suitable type ofdevice, such as integrated circuitry or the like, and can communicatewith the device 4, the first semiconductor element 3, and/or othercomponents. For example, in some embodiments, one or more electroniccomponents 37A can be defined within the semiconductor element 2 (e.g.,buried within the semiconductor element 2 or exposed at the surface 9).In some embodiments, one or more electronic components 37B can bedefined at or on the surface 9 of the semiconductor element 2.

FIG. 2G is a schematic side sectional view of a bonded structure 1,according to various embodiments. FIG. 2G is similar to FIGS. 1A and 2F,except in FIG. 2G, there may not be a cavity defined between the firstand second semiconductor elements 3, 2. Rather, in the embodiment ofFIG. 2G, the first and semiconductor elements 3, 2 may be bonded to oneanother without an intervening cavity. In the illustrated embodiment, aswith the embodiments described herein, the semiconductor elements 3, 2can be bonded to one another by way of an interface structure 10 thatdefines an effectively annular pattern or profile about the interior ofthe elements 3, 2. As explained herein, the semiconductor elements 3, 2can be directly bonded to one another along at least the interfacestructure 10 to define the effectively annular profile, with conductiveand nonconductive interface features defined therein. The effectivelyannular profile of the interface structure 10 can comprise any of thepatterns disclosed herein. Even though there may be no cavity in thebonded structure 1 of FIG. 2G, the interface structure 10 may define aneffective seal so as to protect sensitive electronic circuits orcomponents 37 in the interior of the structure 1 from the outsideenvirons, including, e.g., gases. It should be appreciated that any ofthe embodiments disclosed herein may be used in conjunction with bondedstructures that do not include a cavity.

Moreover, as illustrated in FIG. 2G, the first semiconductor element 3can comprise one or more electronic components 38 formed at or near thesurface of the element 3, and/or within the body of the element 3. Thesecond semiconductor element 3 can also include one or more electroniccomponents 37 formed at or near the surface of the element 2, and/orwithin the body of the second semiconductor element 3. The electroniccomponents 37, 38 can comprise any suitable type of element, such aselectronic circuitry that includes transistors, etc. The components 37,38 can be disposed throughout the elements 3, 2 in any suitablearrangement. In the embodiment of FIG. 2G, the first and second elements3, 2 can comprise any combination of device dies, such as anycombination of processor dies, memory dies, sensor dies, etc. In theillustrated embodiment, the interface structure 10 can be disposed aboutthe periphery of the bonded structure 1 so as to seal the interior ofthe bonded structure 1 from the outside environs. In variousembodiments, therefore, the interior of the bonded structure 1, e.g.,the region within the effectively annular pattern defined by theinterface structure 10, may or may not be directly bonded. In theillustrated embodiment, some components 37, 38 may be disposed within aninterior region of the bonded structure 1, e.g., within the effectivelyclosed profile defined by the interface structure 10. A firstinterconnect of the first semiconductor element 3 and a secondinterconnect of the second semiconductor element 2 can be directlybonded to one another within the interior region of the bonded structure1 to connect components 37, 38 in the respective elements 3, 2. Inaddition, additional components may be disposed outside the interiorregion defined by the interface structure 10. Such additional components(such as integrated device dies) may also be directly bonded to oneanother outside the interior region.

FIGS. 2H and 2I are schematic plan views of interface structures 10 thatcomprise conductive interface features 12 including an array ofconductive dots, as seen from the plan view. In FIG. 2H, the conductiveinterface features 12 comprise a ring of closely spaced dots about thecavity 5 (or the interior of the bonded structure generally). In FIG.2I, the conductive interface features 12 comprise multiple rings ofclosely spaced dots, with an outer ring of features laterally offsetrelative to the inner ring of features so as to improve the sealabilityof the interface structure 10. Although two rings of features 12 areshown in FIG. 2I, it should be appreciated that the conductive features12 can comprise a mesh of dots or discrete shapes spaced from oneanother so as to define the effectively annular pattern. The conductiveinterface features 12 and the nonconductive interface feature 14 cancooperate to define an effectively annular or effectively closed patternthat connects two semiconductor elements. It should be appreciated that,although the dots shown in FIGS. 2H-2I are illustrated as rounded (e.g.,circular or elliptical), in other embodiments, the dots can comprise anysuitable discrete shapes such as polygons. Moreover, as explainedherein, in some embodiments, the conductive interface features 12 (e.g.,the dots) may only act as bonding mechanisms between the twosemiconductor elements 3, 2. In other embodiments, however, some or allconductive interface features 12 may act as electrical interconnects(such as the ends of the interconnects 20 or pads connected thereto) toprovide electrical communication between the semiconductor elements 3,2. It should be appreciated that the features of FIGS. 2H and 2I can becombined with the various other embodiments disclosed herein.

FIG. 2J is a schematic side sectional view of a bonded structure 1having one or more bond pads 65 positioned outside a bonded interfacebetween first and second elements 3, 2 (which may comprise semiconductorelements in some embodiments). FIG. 2K is a top plan view of the bondedstructure 1 shown in FIG. 2J. Unless otherwise noted, components shownin FIGS. 2J-2K may be the same as or generally similar to like numberedcomponents in FIGS. 1A-2I. For example, the bonded structure can includefirst and second elements 3, 2 directly bonded to one another along aninterface structure 10 without an intervening adhesive. In otherembodiments, the first and second elements 3, 2 may be bonded in otherways, such as by way of one or more adhesives. In various embodiments,the bonding layers 11 of each element 3, 2 can include conductiveinterface features that can bond directly to one another along theinterface structure 10. In some embodiments, the conductive interfacefeatures can define a closed shape to seal the interface againstdiffusion as described elsewhere herein. In some embodiments, thebonding layers 11 of each element 3, 2 can include conductive andnon-conductive interface features (not shown) that can bond to define aseal and an effectively closed or effectively annular profile. The firstand second elements 3, 2 can define a cavity 5 in which an integrateddevice is at least partially disposed. In other embodiments, such asthat shown in FIG. 2G, there may be no cavity between the two elements3, 2. In other embodiments, any type of hybrid bond with isolated orembedded conductive portions can be used.

As shown in FIGS. 2J and 2K, the bond pads 65 can be disposed outsidethe effectively closed profile defined by the interface structure 10.For example, the bond pads 65 can be disposed on an outer ledge portion67 of the second element 2. The bond pads 65 can be directly connectedto the circuitry in the second element 2. The bond pads 65 can also beconnected to circuitry in the first element 3 by way of conductivetraces (not shown) defined in the first and/or second elements 3, 2. Thebond pads 65 can be configured to electrically communicate with anexternal component, such as a package or system board, e.g., by wirebonds, solder balls, or other electrical connectors. The effectivelyclosed profile can be defined by element 3, by element 2, or by bothelements 2, 3.

As illustrated in FIG. 2K, the ledge portion 67 can have a ledge widthdx along the side of the bonded structure 1 outside the bonded interfacestructure 10. The ledge width dx may undesirably increase the overallfootprint of the structure 1. In various arrangements, the ledge widthdx can be in a range of 50 microns to 250 microns, or in a range of 100microns to 200 microns. Any suitable number of ledge portions may beprovided about the periphery of the bonded interface structure 10. InFIG. 2K, for example the ledge portion 67 is provided along twoperpendicular or non-parallel sides of the interface structure 10, butin other embodiments, two ledge portions 67 may be provided along twoparallel sides of the interface structure 10, only one ledge portion 67may be provided along only one side of the interface structure 10, ormore than two ledge portions 67 (e.g., three or four) can be providedalong more than two sides of the interface structure 10 (e.g., three orfour sides). Other side numbers are possible with non-rectangularelements.

FIG. 2L is a schematic side sectional view of a bonded structure 1having one or more bond pads 65 disposed at an upper surface 68 of thebonded structure 1, according to various embodiments. FIG. 2M is a topplan view of the bonded structure 1 shown in FIG. 2L. As shown in FIG.2L, the one or more bond pads 65 can be provided at an exterior or uppersurface 68 of the bonded structure 1, e.g., on the upper surface of thefirst element 3. While illustrated as sitting atop the upper surface 68,the skilled artisan will appreciate that the bond pads 65 may berecessed relative to a top surface of the bonded structure or buriedbeneath a passivation layer and exposed by openings therethrough. Asexplained above one or more conductive traces 36 can provide electricalcommunication between various components of the structure 1. In theillustrated embodiment, the traces 36 can connect with the bond pads 65by way of a conductive interconnect 66 extending from a conductive trace36 of the second element 2, through the interface structure 10 (e.g., byway of conductive interface features within the interface structure 10,which may be embedded in non-conductive interface features) and the bodyof the first element 3, to electrically connect to the bond pads 65. Theinterconnects 66 may also extend through at least a portion of thesecond element 2 to connect with traces 36 disposed in the body of thesecond element 2 (e.g., disposed in the bonding layer 11 of the element2). In other embodiments, the interconnects 66 may not penetrate thesecond element 2, e.g., in embodiments in which the traces 36 or otherconductors are disposed at the top surface of the second element 2(e.g., on the top surface of the bonding layer 11 of the element 2). Theconductive traces 36 and interconnects 66 can be separately provided foreach of one or more bond pads 65. In some embodiments, one or more ofthe bond pads 65 may connect to integrated devices or circuitry withinthe first element 3, and thus not be directly associated withinterconnects 66 or traces 36 that communicate through the interface. Ofcourse, the traces 36 and interconnects 66 that communicate withmultiple bond pads 65 at the upper surface 68 should be insulated fromany sealing ring (not shown) formed by direct conductor bonding at theinterface between the first and second elements 3, 2. Although thebonded structure 1 of FIG. 2L includes a cavity 5, in other embodiments,no cavity may be provided. In various embodiments, for example, anintegrated device can be disposed at or near the surface of the element3 (or the element 2), and/or within the body of the element 3 (or theelement 2).

Beneficially, providing the interconnect 66 through the interfacestructure 10 can reduce the overall footprint of the bonded structure 1as compared with the arrangement shown in FIGS. 2J and 2K. For example,by routing the interconnect 66 through the interface structure 10, theledge region of FIGS. 2J and 2K can be eliminated, reducing the lateralfootprint by dx for each ledge region eliminated. In variousembodiments, the embodiment of FIGS. 2L and 2M can increase the numberof bonded structures per wafer in a range of 3% to 125%. For example,for structures 1 with one bond pad ledge region 67, the embodiment ofFIGS. 2L-2M can increase the number of bonded structures per wafer by anamount in a range of 3% to 30%. For structures 1 with two bond pad ledgeregions 67, the embodiment of FIGS. 2L-2M can increase the number ofbonded structures per wafer by an amount in a range of 7% to 60%. Forstructures 1 with three bond pad ledge regions 67, the embodiment ofFIGS. 2L-2M can increase the number of bonded structures per wafer by anamount in a range of 10% to 90%. For structures 1 with four bond padledge regions 67, the embodiment of FIGS. 2L-2M can increase the numberof bonded structures per wafer by an amount in a range of 16% to 125%.

In various embodiments disclosed herein, the bonded structure 1 withbond pads 65 on an upper surface of the bonded structure 1 canbeneficially increase the number of dies per wafer (dpw) (e.g., bondedstructures per wafer) with the elimination of ledges or ledge regionsfrom one, two, three, and/or four sides of the die or bonded structure.Furthermore, FIG. 2N is a chart that plots the percent increase in thenumber of bonded structures or dies per wafer versus die area for bondedstructures in which bond pad ledges have been eliminated on one side,two sides, three sides, or four sides of the bonded structure or die. Asshown in FIG. 2N, for example, the percent increase in the number ofbonded structures or dies per wafer is higher for bonded structures ordies in which the ledges have been eliminated from four sides ascompared to only one side.

FIG. 2O is a schematic side sectional view of a bonded structure 1,according to another embodiment. Unless otherwise noted, componentsshown in FIG. 2O may be the same as or generally similar tolike-numbered components shown in FIGS. 2L and 2M. In FIG. 2L, the firstand second elements 3, 2 are illustrated as being generally laterallycoextensive, e.g., the overall widths of the elements 3, 2 as shown inFIG. 2L are approximately the same. Unlike in FIG. 2L, however, in FIG.2O, one of the elements (e.g., the lower or second element 2) may belarger than the first element 3. For example, as shown in FIG. 2O, thesecond element can have a shelf portion 69 that extends laterally beyondouter edges of the first element 3. Nevertheless, the overall footprintof the bonded structure 1 may be relatively small as compared with thestructure 1 shown in FIGS. 2J-2K. For example, the shelf portion 69 mayonly slightly extend past the outer edges of the first element 3 by adistance d, as shown in FIG. 2O. The distance d may be sufficientlysmall such that wire bonding the first and second elements 3, 2 to padson the shelf portion 69 may be difficult or impossible. In someembodiments, the lateral area or footprint of the second element 2 maybe the same as the lateral area or footprint of the first element 3 (seeFIG. 2L). In FIG. 2O, the lateral area or footprint of the secondelement 2 can be in a range of 100% to 125%, in a range of 100% to 110%,or in a range of 100% to 105% of the area or lateral footprint of thefirst element 3. In various embodiments, no bond pads may be provided onthe shelf portion 69. Indeed, to the extent there is a shelf portion 69,it may be very narrow and insufficiently wide to allow for wire bonding.In other embodiments, the shelf portion 69 may include bond pads inaddition to those on the upper surface of the upper element 3. Invarious embodiments, an entirety of the shelf portion 69 can be coveredby the bonding layer 11. In some embodiments, an additional layer, e.g.,a passivation layer can also be provided over the bonding layer and canextend across the element 2, including over the shelf portion 69. Whilenot shown, the passivation layer may be pierced by conductors connectedto the trace 36 within the footprint of the first element 3, but is notpierced by conductors in the exposed shelf portion 69. Although thetrace 36 in FIGS. 2J, 2L, and 2O is shown as being disposed within thebonding layer 11, it should be appreciated that the trace(s) 36 can bedisposed in the main body of the element 2 (e.g. the bulk silicon orsemiconductor material for semiconductor elements).

The interconnect 66 can be formed in any suitable manner. In someembodiments, the interconnect 66 can be formed prior to bonding thefirst and second elements 3, 2. In other embodiments, the interconnect66 can be formed after bonding the first and second elements 3, 2. Insome embodiments, for example, the interconnect 66 can be formed in avia-first process, in which the interconnect 66 can be initially buriedwithin the first element 3 and exposed through a subsequent removal orthinning process (such as etching, grinding, etc.). In otherembodiments, the interconnect can be formed in a via-last process, inwhich a trench is defined (e.g., etched) in the first element 3, and aninsulating liner and the metallic interconnect 66 are deposited in thetrench. Although the interconnect 66 is illustrated as extending throughthe thickness of the first element 3 in FIG. 2L, in other arrangements,the interconnect 66 may also, or alternatively, extend through thesecond element 2. Moreover, as explained above, in some embodiments, theinterconnect 66 can communicate with the second element 2 by way ofconductive interface features disposed along the interface structure 10.In some embodiments, the interconnect 66 can extend through, and/or canbe defined within, the interface structure 10, such that theinterconnect 66 can form at least part of the conductive interfacefeature(s) of the interface structure 10. For example, in someembodiments, the interconnect 66 can be exposed on a lower surface ofthe first element 3 prior to bonding, and can directly bond to acorresponding conductive feature (which may itself comprise anotherinterconnect) of the second element 2. As with the conductive featuresdescribed above, in various embodiments, barrier, seed and/or insulatinglayer(s) can line trench(es) and/or via(s) of the dielectric, and theinterconnect 36 can be provided over any such liners.

FIG. 3 is a schematic side sectional view of a portion of a bondedstructure 1 that includes a crack stopper 13 connected with theconductive interface features 12 of the interface structure 10. Thecrack stopper 13 includes alternating wider and narrower segments as itvertically connects through back-end-of-line interconnect structureswithin the die, and accordingly can prevent or reduce the propagation ofcracks in one of the semiconductor elements (e.g., the second element2). By introducing low K dielectrics into the back-end of the line(BEOL) interconnect layer of a functional device die, the fractureresistance of the dielectric may be substantially reduced and may becomparable or significantly lower than that of silicon. Therefore,preventing cracking and delamination of the low K dielectric layers atthe edge of a die may be challenging under the stresses that arise fromchip package interactions. Beneficially, cracking at the edge of thechip can be reduced by incorporating the patterned metal interfacestructures (e.g., the crack stopper 13) around the perimeter in the lowK dielectrics that act as a crackstop by increasing the fractureresistance near the edge of the chip.

FIGS. 4A-4C are schematic plan views of bonded structures 10 thatincrease tolerance for misalignments when corresponding interfacefeatures from each of the semiconductor elements 3, 2 are bondedtogether. In some embodiments, the bonded structures 10 of FIGS. 4A-4Ccan be arranged to provide an effective gas seal when correspondingconductive interface features 12, 12′ from adjacent semiconductorelements are misaligned. As explained herein, in various embodiments,the interface structure 10 can be defined by first interface featuresdisposed on the first semiconductor element 3 and second interfacefeatures disposed on the second semiconductor element 2. For example, asshown in FIGS. 4A-4C, a first conductive interface feature 12 and afirst non-conductive interface feature 14 can be disposed on the firstsemiconductor element 3. A second conductive interface feature 12′ and asecond non-conductive interface feature 14′ can be disposed on thesecond semiconductor element 2. The first and second interface featurescan comprise the materials described above in connection with FIGS.1A-2B. For example, in various embodiments, the first and secondconductive interface features 12, 12′ can comprise copper. In variousembodiments, the first and second non-conductive interface features 14,14′ can comprise silicon oxide.

As with the bonded structures 1 of FIGS. 1A-2B, in some embodiments, theinterface structure 10 of FIGS. 4A-4C can extend around the cavity 5and/or integrated device 4 to define an effectively annular pattern,e.g., the conductive features can delimit a complete annulus or anincomplete annulus that define an effectively annular pattern. Disposingthe interface structure 10 in an effectively annular pattern canadvantageously seal the cavity 5 and/or integrated device 4 from gasesentering the bonded structure 1. In other embodiments, however, theinterface structure 10 of FIGS. 4A-4C can be used as an interface forapplications other than, or in addition to, gas sealing. For example,the interface structure 10 of FIGS. 4A-4C can be used in any applicationto account for misalignment when conductive features are bonded to oneanother. In some embodiments, the interface structure 10 of FIGS. 4A-4Ccan provide one or more direct electrical and/or mechanical connectionsbetween the semiconductor elements. In various embodiments, theinterface structure 10 of FIGS. 4A-4C may or may not be disposed aboutthe integrated device 4 in an annular pattern. In some embodiments, forexample, the interface structure 10 may be disposed at a plurality ofdiscrete locations on the corresponding external surfaces of thesemiconductor elements, such as for the interconnects 20 described belowwith respect to FIG. 7C. In such embodiments, the interface structure 10can act as an electrical interconnection between the semiconductorelements. The first and second interface features can be bonded to oneanother in a variety of ways. In some embodiments, the first and secondinterface features can be directly bonded to one another without anintervening adhesive and without the application of pressure and/ortemperature.

In embodiments that utilize direct bonding for the interface structure10, bonding surfaces of the first and second interface features can beprepared. For example, a bonding surface of the first conductiveinterface feature 12 and the first non-conductive interface feature 14can be directly bonded to a corresponding bonding surface of the secondconductive interface feature 12′ and the second non-conductive interfacefeature 14′, without an intervening adhesive and without the applicationof pressure or a voltage. The bonding surfaces can be polished orplanarized, activated, and terminated with a suitable species. Thebonding surfaces can be brought into contact to form a direct bondwithout application of pressure. In some embodiments, the semiconductorelements 3, 2 can be heated to strengthen the bond, for example, a bondbetween the conductive features. Additional details of the directbonding processes used in conjunction with each of the disclosedembodiments may be found throughout U.S. Pat. Nos. 7,126,212; 8,153,505;7,622,324; 7,602,070; 8,163,373; 8,389,378; and 8,735,219, andthroughout U.S. patent application Ser. No. 14/835,379; 62/278,354;62/303,930; and Ser. No. 15/137,930, the contents of each of which arehereby incorporated by reference herein in their entirety and for allpurposes.

In the structure 10 of FIG. 4A, the conductive interface features 12,12′ are relatively thin, such that dishing from polishing can be avoidedand direct metal-to-metal bonding facilitated. If the respectiveinterface features are laterally misaligned, however, a conductive bond35 between the features 12, 12′ is relatively small. The conductivebonds 35 shown in FIG. 4A may comprise isolated regions of contact,which may provide an inadequate gas seal (and/or an inadequateelectrical connection).

Accordingly, as shown in FIGS. 4B-4C, the conductive interface features12, 12′ can be made sufficiently wide so as to ensure adequateconductivity of electrical connections and also provide a betterdiffusion barrer. The thick conductive features 12, 12′ of FIGS. 4B-4Ccan advantageously enable larger conductive bonds 35, and also improvethe gas sealing capabilities (and/or electrical connections) of theinterface structure 10. In FIG. 4B, for example, the thickness of theconductive features 12, 12′ can be made to be thicker than a maximummisalignment tolerance of the bonding procedure. Thus, if a bondingprocedure has a misalignment tolerance of T, then the lateral thicknessof the conductive interface features 12, 12′ can be greater than orequal to T. In various direct bonding procedures, for example, themisalignment tolerance T can be in a range of 0.1 microns to 25 microns.Dimensioning the thickness of the conductive feature 12, 12′ to equal orexceed the maximum misalignment tolerance T of the bonding process canensure that the conductive bond 35 forms a closed structure.

In the embodiment of FIG. 4C, the thickness of the conductive interfacefeatures 12, 12′ can be selected to be larger than the space providedfor the intervening non-conductive interface features 14, 14′. Thus, inFIG. 4C, the conductive features 12 can be thicker than thenon-conductive features 14, 14′. Dimensioning the conductive features 12in such a manner can ensure that the conductive features 12, 12′ matealong a continuous interface. Accordingly, the relatively thickconductive features 12, 12′ of FIGS. 4B-4C can provide effectiveconnection between conductive interface features 12, 12′ during bondingeven in the presence of misalignment, and a continuous interface canprovide an annular or mostly annular barrier to diffusion.

FIGS. 5A-5D are schematic plan views of an interface structure 10 thatincrease tolerance for misalignments when corresponding interfacefeatures 10A, 10B on each semiconductor element 3, 2 are bondedtogether, while providing an effective metal diffusion barrier. Asexplained above in connection with FIGS. 4A-4C, it can be important toaccount for misalignments when bonding (e.g., direct bonding) twocorresponding interface features 10A, 10B. The interface features 10A,10B can be disposed on exterior surfaces of the first and secondsemiconductor elements 3, 2, respectively. The interface features 10A,10B can comprise one or more conductive interface features 12, 12′,which can also be embedded in or coupled with one or more non-conductiveinterface features 14, 14′. The conductive interface features 12, 12′can be brought together and directly bonded without an interveningadhesive in some embodiments. In some embodiments, the non-conductiveinterface features 14, 14′ can also be directly bonded to one another.In other embodiments, an adhesive can be used to bond the elements. Theconductive features 12, 12′ can define a conductive bond 35 alongregions where the features 12, 12′ overlap with one another.

To increase tolerance for misalignments, the conductive interfacefeatures 12, 12′ can comprise a plurality of wide sections 16alternately arranged and connected with a plurality of narrow sections15. For example, as shown in FIG. 5A, each wide section 16 can beconnected between two narrow sections 15, and each narrow section 15 canbe connected between two wide sections 16. The narrow section 15 canhave a first width tin a range of 0.1 microns to 25 microns. The widesection can have a second width w less than t and in a range of 0.5microns to 50 microns. Moreover, as shown in FIG. 5A, the wide sections16 can be spaced from one another by a first distance g in which theintervening non-conductive interface feature 14 can be disposed. thewide and narrow sections 16, 15 can be connected end-to-end, the narrowsections 15 can have a length that is the same as the first distance g.The first distance g can be in a range of 0.1 microns to 50 microns. Thethin sections can be spaced from one another by a second distance h,which may also comprise a length of the wide sections 16. The seconddistance h can be in a range of 0.2 microns to 50 microns. Moreover, anoutermost edge of the wide sections 16 can be offset relative to anoutermost edge of the narrow sections 15 by a lateral offset x, which asexplained below can correspond to the bonding procedure's maximumalignment tolerance in the x direction. The lateral offset x can be in arange of 0.1 microns to 25 microns.

Advantageously, the wide segments 16 can be provided to improve the gassealing capabilities of the bonded structure 1, as explained above. Thenarrow segments 14 can be provided to reduce the effects of dishing thatmay occur due to polishing, thereby facilitating direct conductor toconductor bonding. FIG. 5B illustrates the interface structure 10 afterbonding in which there is little to no misalignment of the respectiveinterface features 10A, 10B. As shown in FIG. 5B, the conductivefeatures 12, 12′ completely overlap one another at a half-pitch offsetin the y-direction as shown in FIG. 5A such that the bonded conductiveregions provide closed pathways at a large conductive bond 35. As shownin FIG. 5B, in the case where there is little to no misalignment, theconductive features 12, 12′ completely overlap laterally at theconductive bond 35, i.e., parallel to the lateral offset x, because thelateral offset of the outermost edge of the wide sections 16 can beselected to correspond to the bonding procedures' maximum alignmenttolerance. For example, for a lateral misalignment tolerance x for aparticular bonding procedure, the first and second widths t, w can beselected to satisfy the relationship x≤(w−t)/2. For a longitudinalmisalignment tolerance y during bonding, for a particular bondingprocedure, the first and second distances g, h can be selected tosatisfy the relationship y≤(h−g)/2. Satisfying these relationshipsensure that a continuous overlap, or bond line, between the conductivefeatures 12, 12′ of the different semiconductor elements 3, 2.

FIG. 5C illustrates the bonded interface structure 10 when the interfacefeature 10A, 10B are misaligned laterally by the misalignment tolerancex and longitudinally by the misalignment tolerance y. As shown in FIG.5C, even when the interface features 10A, 10B are misaligned by x and yfor a particular bonding procedure, the resulting bonded interfacestructure 10 comprises significant and continuous overlap between theconductive interface features 12, 12′ at the conductive bond 35, whichcan provide an effectively annular diffusion barrier, e.g., a completelyannular or mostly annular barrier to diffusion.

FIG. 5D illustrates the bonded interface structure 10 when the interfacefeatures 10A, 10B are misaligned laterally by the misalignment tolerancex plus the first width t, with longitudinal misalignment less than(h−g)/2. As shown in FIG. 5D, when there is longitudinal misalignmentless than (h−g)/2 (e.g., parallel to y), the bonded interface structure10 of FIG. 5D can accommodate lateral misalignments that are even largerthan the misalignment tolerance x of the bonding procedure, because theadditional width of the narrow sections 15 can contribute additionalbonding regions at the conductive bond 35 when there is longitudinalmisalignment less than (h−g)/2. While the overlapping bond region islaterally less wide than in FIG. 5C, the metal to metal bond interfaceremains continuous and provides a better diffusion barrier than, forexample, oxide.

FIGS. 6A-6B are schematic plan views of an interface structure 10 thatincreases tolerance for misalignments when corresponding interfacefeatures 10A, 10B on each semiconductor element 3, 2 are bondedtogether, according to another embodiment. In the embodiment of FIGS.6A-6B, the non-conductive interface features 14, 14′ can comprise aplurality of inner regions 114 a and a plurality of outer regions 114 b.The inner regions 114 a can be completely surrounded (in a horizontalplane) by the conductive interface features 12, 12′. In the illustratedembodiment, the plurality of the conductive interface features 12, 12′can comprise a number of blocks 17 that are disposed around (e.g.,completely around) the inner regions 114 a of the non-conductiveinterface regions 14, 14′. The outer regions 114 b of the non-conductiveinterface regions 14, 14′ can be disposed in gaps between adjacent outerblocks 17.

In some embodiments, a first width t₁ of the blocks 17 can be greaterthan a second width t₂ of the inner regions 114 a and/or the outerregions 114 b. For example, in some embodiments, the first width t₁ ofthe blocks 17 can be in a range of 0.2 microns to 25 microns. The secondwidth t₂ of the inner regions 114 a and/or the outer regions 114 b canbe in a range of 0.1 microns to 20 microns. Dimensioning the blocks 17to be larger than the regions 114 a, 114 b can enable the conductivefeatures 12, 12′ to have significant overlapping conductive bond 35, asshown in the bonded interface structure 10 of FIG. 6B.

FIG. 7A is a schematic plan view of a conductive interface feature 10Ain which a plurality of inner regions 114 a of non-conductive interfacefeatures 14 are disposed within (surrounded by) a lattice. For example,the interface feature 10A shown in FIG. 7A comprises a crosswise gridstructure defined by intersecting conductive interface features 12. FIG.7B is a schematic plan view of a bonded interface structure 10 formed bybonding two interface features 10A, 10B. As shown in FIG. 7A, theconductive feature 12 can include a plurality of wide blocks 18interconnected by narrow conductive segments 19. The wide blocks 18 canprovide improved gas sealing capabilities, and the narrow conductivesegments 19 can be provided to avoid the negative effects of dishing dueto polishing procedures, thereby facilitating direct metal to metalbonds. In FIG. 7A, the blocks 18 and segments 19 are arranged in a gridin which the conductive features 12 are disposed perpendicular to oneanother. However, in other embodiments, the features 12 can be arrangednon-perpendicularly relative to one another.

In FIGS. 7A-7B, the blocks 18 can have a first width t₁ that is largerthan a second width t₂ of a gap G disposed between adjacent blocks 18.For example, in some embodiments, the first width t₁ can be in a rangeof 0.2 microns to 50 microns. The second width t₂ can be in a range of0.1 microns to 25 microns. As shown in FIG. 7B, spacing the blocks 18 insuch a manner can beneficially enable large regions of overlap betweenthe conductive features 12 along the conductive bond 35, and result inmultiple adjacent metal bond lines, which can be beneficial for sealingthe bonded structure 1 from gases.

Although the lattice shown in FIGS. 7A-7B comprises a grid ofintersecting conductive lines, in other embodiments, the lattice cancomprise curved, periodic, or irregular shapes. For example, in someembodiments, the lattice can comprise a honeycomb structure ofinterconnected polygons. In some embodiments, the lattice can comprise aplurality of triangles, a herringbone pattern, or any other suitablelattice of repeating shapes.

FIG. 7C is a schematic plan view of the bonded interface structure 10 ofFIG. 7B, with a plurality of electrical interconnects 20 disposed withinthe inner regions 114 a of the non-conductive interface features 14. Asexplained above in connection with FIG. 2B, it can be advantageous toincorporate additional conductive electrical interconnects 20 into theinterface structure 10. Doing so enables the bonded structure 1 toprovide a gas seal and electrical communication for a large number ofsignal, power and/or ground lines between the semiconductor elements 3,2. In the embodiment of FIG. 7C, for example, the conductive interfacefeatures 12 and the non-conductive interface features 14 can provide amechanical connection between the semiconductor elements 3, 2 that actsas an effective barrier to gases entering the structure. The conductivefeatures 12 can comprise elongate features with a length greater than awidth. The electrical interconnects 20 can be disposed within the innerregions 114 a and can be electrically isolated from the conductivefeatures 12. The interconnects can extend vertically from the firstsemiconductor element 3 to the second semiconductor element 2 throughthe non-conductive features 14 to provide electrical communicationbetween the semiconductor elements 3, 2. It will be understood that theeffectively annular patter, e.g., a completely or mostly annularpattern, created by overlap and bonding of the two conductive features12 can also serve as additional or sole electrical connection betweenthe two semiconductor elements 3, 2.

Thus, in the embodiments of FIGS. 4B-7C, the first semiconductor element3 can comprise a first pattern of repeating shapes formed fromconductive lines on an exterior surface of the first semiconductorelement 3. The first pattern can comprise a first conductive interfacefeature 12 spaced apart by a first spacing from a second conductiveinterface feature 12, with a first non-conductive interface feature 14being disposed between the first and second conductive interfacefeatures 12. The first conductive interface feature 12 can have a firstwidth that is greater than the first spacing. The second semiconductorelement 2 can have a second pattern of repeating shapes formed fromconductive lines on an exterior surface of the second semiconductorelement 2. The second pattern can comprise a third conductive interfacefeature 12 spaced apart by a second spacing from a fourth conductiveinterface feature 12, with a second non-conductive interface feature 14being disposed between the third and fourth conductive interfacefeatures 12. The third conductive interface feature 12 can have a secondwidth that is greater than the second spacing. The first and secondconductive interface features 12 can be bonded to the third and fourthconductive interface features 12 to define an interface structure 10.Even though the first and second patterns may be laterally offsetrelative to one another, the bonded first and second patterns cannevertheless delimit a continuous conductive bond region 35 along theinterface structure 10.

FIG. 8 is a schematic diagram of an electronic system 80 incorporatingone or more bonded structures 1, according to various embodiments. Thesystem 80 can comprise any suitable type of electronic device, such as amobile electronic device (e.g., a smartphone, a tablet computing device,a laptop computer, etc.), a desktop computer, an automobile orcomponents thereof, a stereo system, a medical device, a camera, or anyother suitable type of system. In some embodiments, the electronicsystem 80 can comprise a microprocessor, a graphics processor, anelectronic recording device, or digital memory. The system 80 caninclude one or more device packages 82 which are mechanically andelectrically connected to the system 80, e.g., by way of one or moremotherboards. Each package 82 can comprise one or more bonded structures1. The system 80 shown in FIG. 8 can comprise any of the bondedstructures 1 and associated interface structure 10 shown and describedherein.

In one embodiment, a bonded structure comprising is disclosed. Thebonded structure can include a first element having a first interfacefeature, and a second element having a second interface feature. Thebonded structure can include an integrated device coupled to or formedwith the first element or the second element. The first interfacefeature can be directly bonded to the second conductive interfacefeature to define an interface structure. The interface structure can bedisposed around the integrated device to define an effectively closedprofile to connect the first and second elements. The effectively closedprofile can substantially seal an interior region of the bondedstructure from gases diffusing into the interior region from the outsideenvirons.

In another embodiment, a bonded structure comprises a first element anda second element. The bonded structure can include an integrated devicecoupled to or formed within the first element or the second element. Aninterface structure can be disposed between the first element and thesecond element. The interface structure can comprise a first conductiveinterface feature extending in a direction from the first element to thesecond element, a second conductive interface feature extending in adirection from the first element to the second element, and a solidstate non-conductive interface feature disposed laterally between thefirst and second conductive interface features. The interface structurecan be disposed about the integrated device to define an effectivelyclosed profile to connect the first element and the second element.

In another embodiment, a bonded structure comprises a first element anda second element. An integrated device can be coupled to or formed withthe first element or the second element. An interface structure can bedisposed between the first element and the second element, the interfacestructure extending in a direction from the first element to the secondelement. The interface structure can include a first elongate conductiveinterface feature extending in a direction from the first element to thesecond element and a second elongate conductive interface featureextending in a direction from the first element to the second element.The first and second elongate conductive interface features can bespaced apart by an intervening non-conductive interface featureextending in a direction from the first element to the second element.Each of the first and second elongate conductive interface features canhave a length greater than a width. An electrical interconnect can be inelectrical communication with the integrated device, the electricalinterconnect extending from the first element to the second element. Theelectrical interconnect can extend through the interveningnon-conductive interface feature between the first and second conductiveinterface features.

In another embodiment, a bonded structure comprises a first elementhaving a first pattern of repeating shapes formed from conductive lineson an exterior surface of the first element. The first pattern cancomprise a first conductive interface feature spaced apart by a firstspacing from a second conductive interface feature, a firstnon-conductive interface feature being disposed between the first andsecond conductive interface features. The first conductive interfacefeature can have a first width that is greater than the first spacing.The bonded structure can comprise a second element having a secondpattern of repeating shapes formed from conductive lines on an exteriorsurface of the second element. The second pattern can comprise a thirdconductive interface feature spaced apart by a second spacing from afourth conductive interface feature. A second non-conductive interfacefeature can be disposed between the third and fourth conductiveinterface features, the third conductive interface feature having asecond width that is greater than the second spacing. The first andsecond conductive interface features can be bonded to the third andfourth conductive interface features to define an interface structure.The first and second patterns can be laterally offset relative to oneanother but delimiting a continuous conductive bond region along theinterface structure.

In another embodiment, a bonded structure is disclosed. The bondedstructure can include a first element and a second element. Anintegrated device can be coupled to or formed with the first element orthe second element. An interface structure can be disposed between thefirst element and the second element. The interface structure cancomprise a first conductive interface feature laterally enclosing theintegrated device. The conductive interface feature can continuouslyextend between the first and second elements to form at least one of anelectrical, mechanical, or thermal connection between the two elements.A non-conductive interface feature can continuously extend between thefirst and second elements.

In another embodiment, a bonded structure can include a first elementhaving a first interface feature and a second element having a secondinterface feature. The first interface feature can be bonded to thesecond interface feature to define an interface structure. A conductivetrace can be disposed in or on the second element. A bond pad can beprovided at an upper surface of the first element and in electricalcommunication with the conductive trace. An integrated device can becoupled to or formed with the first element or the second element.

In another embodiment, a bonded structure can comprise a first elementhaving a first interface feature and a second element having a secondinterface feature. The first interface feature can be directly bonded tothe second interface feature without an intervening adhesive to definean interface structure. A bond pad can be disposed at an upper surfaceof the first element. An integrated device can be coupled to or formedwith the first element or the second element. An electrical interconnectcan extend from the bond pad through the first element to electricallyconnect to the integrated device.

In another embodiment, a method of forming a bonded structure isdisclosed. The method can comprise providing a first element having afirst interface feature and a second element having a second interfacefeature. A conductive trace can be disposed in or on the second element.The method can comprise bonding the first interface feature and thesecond interface feature. A bond pad can be disposed at an upper surfaceof the first element and in electrical communication with the conductivetrace. An integrated device can be coupled to or formed with the firstelement or the second element.

For purposes of summarizing the disclosed embodiments and the advantagesachieved over the prior art, certain objects and advantages have beendescribed herein. Of course, it is to be understood that not necessarilyall such objects or advantages may be achieved in accordance with anyparticular embodiment. Thus, for example, those skilled in the art willrecognize that the disclosed implementations may be embodied or carriedout in a manner that achieves or optimizes one advantage or group ofadvantages as taught or suggested herein without necessarily achievingother objects or advantages as may be taught or suggested herein.

All of these embodiments are intended to be within the scope of thisdisclosure. These and other embodiments will become readily apparent tothose skilled in the art from the following detailed description of theembodiments having reference to the attached figures, the claims notbeing limited to any particular embodiment(s) disclosed. Although thiscertain embodiments and examples have been disclosed herein, it will beunderstood by those skilled in the art that the disclosedimplementations extend beyond the specifically disclosed embodiments toother alternative embodiments and/or uses and obvious modifications andequivalents thereof. In addition, while several variations have beenshown and described in detail, other modifications will be readilyapparent to those of skill in the art based upon this disclosure. It isalso contemplated that various combinations or sub-combinations of thespecific features and aspects of the embodiments may be made and stillfall within the scope. It should be understood that various features andaspects of the disclosed embodiments can be combined with, orsubstituted for, one another in order to form varying modes of thedisclosed implementations. Thus, it is intended that the scope of thesubject matter herein disclosed should not be limited by the particulardisclosed embodiments described above, but should be determined only bya fair reading of the claims that follow.

What is claimed is:
 1. A bonded structure comprising: a first elementhaving an upper surface and a lower surface, the lower surface of thefirst element including a first interface feature; a second elementhaving an upper surface and a lower surface, the upper surface of thesecond element including a second interface feature; the first interfacefeature of the first element being directly bonded to the secondinterface feature of the second element without an intervening adhesiveto define a bonded interface of the bonded structure, the bondedinterface including conductive and non-conductive features, at least aportion of the conductive feature of the bonded interface substantiallysurrounding an interior region of the bonded structure; a conductivetrace disposed in or on the second element; a bond pad outside of thebonded interface at the upper surface of the first element or the uppersurface of the second element, the bond pad being in electricalcommunication with the conductive trace of the second element; and anintegrated electronic device formed within the first element or thesecond element.
 2. The bonded structure of claim 1, further comprising aconductive sealing ring substantially surrounding the interior region ofthe bonded structure.
 3. The bonded structure of claim 1, the interiorregion includes a cavity.
 4. The bonded structure of claim 1, wherein nocavity is disposed in the bonded structure.
 5. The bonded structure ofclaim 1, wherein the conductive feature of the bonded interface definean effectively closed profile substantially sealing the interior regionof the bonded structure from gases diffusing into the interior region.6. The bonded structure of claim 1, wherein the bond pad is formed atthe upper surface of the first element, further comprising an electricalinterconnect extending from the conductive trace through the bondedinterface to connect to the bond pad.
 7. The bonded structure of claim1, within the second element comprises a second semiconductor element,further comprising a crack stopper structure extending verticallythrough back end of line interconnect structures of the secondsemiconductor element.
 8. The bonded structure of claim 1, wherein thenon-conductive feature of the bonded interface comprise silicon oxide.9. The bonded structure of claim 1, wherein the bond pad is formed atand recessed relative to the upper surface of the first element.
 10. Thebonded structure of claim 1, wherein a lateral area of the secondelement is larger than a lateral area of the first element and the bondpad is formed in a ledge area of the second element outside of thebonded interface.
 11. The bonded structure of claim 2, wherein theconductive sealing ring is part of the conductive feature of the bondedinterface.
 12. The bonded structure of claim 3, wherein the integratedelectronic device is disposed in the cavity.
 13. The bonded structure ofclaim 7, wherein the crack stopper structure is connected to at leastone of the conductive feature of the bonded interface.
 14. The bondedstructure of claim 7, wherein the wherein the crack stopper structureextends around a perimeter of the second semiconductor element tosurround the interior region of the bonded structure.
 15. A bondedstructure comprising: a first element having an upper surface and alower surface, the lower surface of the first element including a firstinterface feature; a second element having an upper surface and a lowersurface, the upper surface of the second element including a secondinterface feature; the first interface feature of the first elementbeing directly bonded to the second interface feature of the secondelement without an intervening adhesive to define a bonded interface ofthe bonded structure, the bonded interface substantially surrounding aninterior region of the bonded structure, the bonded interface includingconductive and non-conductive features; a bond pad at the upper surfaceof the first element; circuitry formed in the second element; and anelectrical interconnect extending through the bonded interface toelectrically connect the circuitry of the second element to the bond padof the first element.
 16. The bonded structure of claim 15, wherein thefirst element comprises a first semiconductor element, and the firstinterface feature includes an annular conductive feature extendingvertically from the bonded interface into the first semiconductorelement.
 17. The bonded structure of claim 15, wherein the secondelement comprises a second semiconductor element, and the secondinterface feature includes an annular conductive feature extendingvertically from the bonded interface into the second semiconductorelement.
 18. The bonded structure of claim 15, further comprising aconductive trace in or on the second element, the conductive traceproviding electrical communication between the circuitry of the secondelement and the electrical interconnect.
 19. The bonded structure ofclaim 15, wherein the conductive features of the bonded interface definea closed profile substantially sealing the interior region of the bondedstructure from gases diffusing into the interior region.
 20. The bondedstructure of claim 15, wherein conductive features of the bondedinterface form an incomplete annular pattern.
 21. The bonded structureof claim 15, wherein the second element includes a crack stopperstructure surrounding the interior region of the bonded structure andextending vertically through back end of line interconnect structures ofthe second element.
 22. The bonded structure of claim 18, furthercomprising a cavity in the interior region of the bonded structure. 23.The bonded structure of claim 22, further comprising a MEMS element atleast partially disposed in the cavity, the MEMS element electricallycommunicating with the interconnect and the bond pad.
 24. The bondedstructure of claim 20, wherein the conductive features of the bondedinterface comprise multiple conductive segments.
 25. The bondedstructure of claim 24, wherein the multiple conductive segments comprisean array of conductive dots.
 26. A method of forming a bonded structure,the method comprising: providing a first element having an upper surfaceand a lower surface, the lower surface of the first element including afirst interface feature; providing a second element having an uppersurface and lower surface, the upper surface of the second elementhaving a second interface feature, a conductive trace being disposed inor on the second element; directly bonding the first interface featureto the second interface feature to define a bonded interface of thebonded structure, the bonded interface including conductive andnon-conductive features, the bonded interface surrounding a cavityregion within the bonded structure; and electrically connecting a bondpad disposed at the upper surface of the first element and with theconductive trace of the second element.
 27. The method of claim 26,further comprising providing an electrical interconnect extending fromthe bond pad through the first element to electrically connect to theconductive trace.
 28. The method of claim 26, further comprisingproviding a MEMS element within the cavity, the MEMS element being inelectrical communication with the bond pad.